The Efficiency of IP Fast ReRoute Depending on Network Topology

OData support
Dr. Tapolcai János
Department of Telecommunications and Media Informatics

The expanding services containing more and more time-dependent QoS (Quality of Service) parameters. Delay, jitter and the minimum transfer rate criterions make an increasing demand upon the recent networks. On the contrary the enlarged networks have to meet the safety requirements of the transfer.

This thesis is to make the reader to understand the differences of the traditionally used routing protocols’ protection methods and the recently emerging, reactive protection routing method, the IPFRR (IP Fast ReRoute). Based on IPFRR we aim to show a “Protection Routing” algorithm, which calculates the primary and secondary next-hops of the routers to a pre-selected destination.

In the first section we dicuss the basics of the graph theory, and how networks can be represented as graph called topology. The basics of routing are presented in section two so the reader can learn the different classifications of routing methods how can we arrive at a right decision. In section three the main topic is the OSPF (Open Shortest Path First) routing protocol and we discuss its protection methods in section four. In section five we present two IPFRR methods, the LFA (Loop Free Alternates) and O2 (Out-degree 2).

The last two sections of the thesis are about the “Protection Routing” algorithm. First of all we specify the main requirements of our algorithms, the way how we reach them and what kind of problems we are facing to. The end of section six contains the exact algorithm written in pseudo code and the explanation of the used key words. This algorithm is implemented in C++ using a Hungarian template project called LEMON. We show the main effects of the routing algorithm using two topology graph and a test program with many screenshots and detailed explanations.


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